Board directions centralise delegation of income-tax powers, assigning Assessing Officer functions and specifying jurisdictional criteria. The Board may direct income-tax authorities on the exercise of their powers and functions, authorise higher-ranking authorities to perform lower authorities' functions, and permit subordinate authorities to issue orders allocating jurisdiction by territorial area, persons, incomes, or cases. The Board can assign functions to specified senior officers and empower other officers to perform Assessing Officer duties, with statutory references to the Assessing Officer deemed to refer to the designated delegate and certain approval requirements not applying. The Board may also require concurrent exercise of powers by multiple Assessing Officers and issue notifications prescribing returns and the responsible authority.